| 1 | package dbreads |
| 2 | |
| 3 | import ( |
| 4 | "encoding/binary" |
| 5 | "encoding/json" |
| 6 | "errors" |
| 7 | "io" |
| 8 | |
| 9 | "github.com/carlosframework/platform/internal/dbdoor" |
| 10 | ) |
| 11 | |
| 12 | // ProtocolVersion is the worker protocol's version, answered in hello. A |
| 13 | // worker that speaks another one never advertises anything (spec §7.1). |
| 14 | const ProtocolVersion = 1 |
| 15 | |
| 16 | // Frames are one type byte, a four-byte big-endian length and the payload, |
| 17 | // at most maxFrame bytes (spec §8.3: length-framed with a fixed maximum). |
| 18 | const ( |
| 19 | maxFrame = 1 << 20 |
| 20 | fileFrameBytes = 256 << 10 |
| 21 | outputFrameBytes = 64 << 10 |
| 22 | ) |
| 23 | |
| 24 | const ( |
| 25 | frameHello byte = 'H' // agent: the readiness probe |
| 26 | frameHelloReply byte = 'h' // worker: its version and its view of its sandbox |
| 27 | frameHeader byte = 'P' // agent: the plan |
| 28 | frameFile byte = 'F' // agent: file bytes, in the header's order |
| 29 | frameReady byte = 'R' // worker: restored and checked; runs nothing yet |
| 30 | frameRun byte = 'X' // agent: check B passed; the statement |
| 31 | frameStop byte = 'S' // agent: end without running |
| 32 | frameOutput byte = 'O' // worker: output bytes |
| 33 | frameEnd byte = 'E' // worker: how it ended |
| 34 | ) |
| 35 | |
| 36 | var ( |
| 37 | errFrameTooLarge = errors.New("dbreads: frame over the protocol's maximum") |
| 38 | errProtocol = errors.New("dbreads: unexpected frame") |
| 39 | ) |
| 40 | |
| 41 | type hello struct { |
| 42 | V int `json:"v"` |
| 43 | } |
| 44 | |
| 45 | // HelloReply is the worker's answer to the probe: its protocol version and |
| 46 | // what it can see of the box (spec §7.1). A sandboxed worker sees only the |
| 47 | // loopback interface, an empty /data and no /etc/carlos. |
| 48 | type HelloReply struct { |
| 49 | V int `json:"v"` |
| 50 | Interfaces []string `json:"interfaces"` |
| 51 | DataEntries int `json:"data_entries"` |
| 52 | EtcReadable bool `json:"etc_readable"` |
| 53 | // Errors names every observation the worker could not make. A probe |
| 54 | // fails on any: an unobserved sandbox is not a sandbox. |
| 55 | Errors []string `json:"errors,omitempty"` |
| 56 | } |
| 57 | |
| 58 | type planHeader struct { |
| 59 | V int `json:"v"` |
| 60 | Op string `json:"op"` |
| 61 | Files []dbdoor.LTXFile `json:"files"` |
| 62 | Target uint64 `json:"target"` |
| 63 | MaxRestored int64 `json:"max_restored"` |
| 64 | } |
| 65 | |
| 66 | type readyMsg struct { |
| 67 | TXID uint64 `json:"txid"` |
| 68 | } |
| 69 | |
| 70 | type runMsg struct { |
| 71 | SQL string `json:"sql"` |
| 72 | } |
| 73 | |
| 74 | type endMsg struct { |
| 75 | Code string `json:"code"` |
| 76 | Error string `json:"error"` |
| 77 | } |
| 78 | |
| 79 | // writeFrame writes one frame in a single Write. |
| 80 | func writeFrame(w io.Writer, typ byte, p []byte) error { |
| 81 | if len(p) > maxFrame { |
| 82 | return errFrameTooLarge |
| 83 | } |
| 84 | buf := make([]byte, 5, 5+len(p)) |
| 85 | buf[0] = typ |
| 86 | binary.BigEndian.PutUint32(buf[1:], uint32(len(p))) |
| 87 | _, err := w.Write(append(buf, p...)) |
| 88 | return err |
| 89 | } |
| 90 | |
| 91 | func writeJSONFrame(w io.Writer, typ byte, v any) error { |
| 92 | p, err := json.Marshal(v) |
| 93 | if err != nil { |
| 94 | return err |
| 95 | } |
| 96 | return writeFrame(w, typ, p) |
| 97 | } |
| 98 | |
| 99 | func readFrame(r io.Reader) (byte, []byte, error) { |
| 100 | var hdr [5]byte |
| 101 | if _, err := io.ReadFull(r, hdr[:]); err != nil { |
| 102 | return 0, nil, err |
| 103 | } |
| 104 | n := binary.BigEndian.Uint32(hdr[1:]) |
| 105 | if n > maxFrame { |
| 106 | return 0, nil, errFrameTooLarge |
| 107 | } |
| 108 | p := make([]byte, n) |
| 109 | if _, err := io.ReadFull(r, p); err != nil { |
| 110 | return 0, nil, err |
| 111 | } |
| 112 | return hdr[0], p, nil |
| 113 | } |
| 114 | |
amadan